The invention relates to a hydraulic system and method, in particular for controlling a fastener for a container evacuator that evacuates silicone gum or other viscous material from a drum to a compounding system.
In a compounding system, a viscous material is fed to a processing line where feed is mixed and additives are injected in proportions to produce a customized product. The feed material for these processes can be delivered in various containers. When delivered, the material must be removed from the container for processing. For example, a compounding system can require emptying material such as silicone gum from drums or similar containers. However, the feed material may be very viscous and resistant to flow and hence, resistant to removal from the delivery container.
Some container emptying processes use a plunger to drive through the container content to express the content for further processing. A considerable amount of pressure is needed in these processes to express a viscous material such as a silicone gum. The high expressing force exposes the materials container to very high mechanical stress. For reasons of weight and expense, the containers are usually designed with very thin walls and a structure that is just sufficient to avoid damage to the container during transport. The container is not designed to withstand stress imposed during an emptying operation and the high pressure developed during the emptying operation can easily burst a container structure.
Reinforcing split metal sleeves or half-shells can be placed around a container during an emptying operation to provide some structural integrity and resistance to bursting. However, the mounting and closing off of the sleeves and half-shells can be very complicated operations, requiring considerable manual labor. The sleeve or half shells are particularly vulnerable to bursting where they are fastened together. Another disadvantage is that the sleeves or half-shells must be adapted in an exact manner to the outside container dimensions thus sometimes requiring an inventory of sleeves or half-shells to accommodate various sized containers.
Commonly assigned and copending patent application Knox et al., Ser. No. 11/536,700, filed Sep. 29, 2006 and entitled FASTENER FOR A VISCOUS MATERIAL CONTAINER EVACUATOR AND METHOD teaches a secure enclosure for a viscous material container evacuator and method to remove viscous material from a delivery container to a processing system. The viscous material container evacuator comprises: a chamber to hold a container and a plunger axially and slidably accommodated within the chamber to express material from the container; at least one hinged closure that closes to define the chamber and to securely enclose the container; and at least one motor activated fastener that secures the closure around the container. However, while the motor activated fastener is advancement, the fastener is only as secure a closure for the chamber as its particular activating mechanism. Accordingly, there remains a need to provide an activating mechanism for a fastener to securely close a viscous material container evacuator